This invention relates to the field of centrifugal test rotors having article carrying adapters, and in particular to channel belts for carrying integrated circuit chip within a bowl shaped centrifugal test rotor.
Modern integrated circuits (ICs) are packaged in a compact ceramic or plastic structure to isolate the microelectronic circuitry contained therein, and ensure that the circuitry will perform under various operational environments. A properly designed IC package protects the microelectronics contained within the package from those environmental effects which tend to interfere with the reliable operation of the circuit. Depending on the intended use of the IC chip, the packaging requirements may be simple, such as when the IC chip will reside within a stationary household appliance. An extremely complicated IC chip package design may result where the circuit is intended for military or aerospace applications where it may be subjected to a variety of sever environmental conditions.
The IC chip package must therefore take into account electrical, thermal, chemical, magnetic, radiant, and mechanical conditions. The IC package must isolate and shield the electronic circuitry carried within the package. The packaging must provide a pathway to dissipate thermal energy generated within the circuit in a safe and nondestructive manner. The chip must be protected from chemical corrosion, external radiation, and external magnetic fields.
Mechanically, the packaging which surrounds the microelectronics contained within the IC chip must be strong enough to withstand stresses which occur during and after assembly and connection with other package circuits on a complex circuit board or system. These stresses include bending of the metal leads, dropping and soldering of circuits. During fabrication and operation, the IC package must withstand exposure to certain levels of shock, acceleration, vibration, welding heat, temperature cycling, moisture, and lead stress.
Various test have been designed to ensure that the IC package meets the design and operational criteria for a given intended-use environment. These tests sometimes include subjecting the IC package to acceleration and gravitational forces through the use of a centrifugal test rotor. The primary objective of the force is to insure integrity of the wire bonds. During manufacture very small wires are bonded at one end to pads on the chip and at the other end to the external package leads. Bonds of low integrity become disconnected under high gravitational forces imposed by centrifugation. Subsequent electrical testing then can identify faulty components.
Generally, the centrifugal test rotor is an open bowl-shaped rotor adapted to receive a flexible belt having a plurality of fixed walled, U-shaped compartments or channels for carrying IC chip components.
One or more integrated circuit packages were inserted into each fixed wall channel. Because the opposite pairs of leads in integrated circuits are not at precise 90.degree. angles to the chip but are purposely manufactured to extend slightly outwardly, installation and removal forces are required to flex the chip leads to fit within the channels and to remove the chips from the channels after centrifugation. In the prior art designs, the fixed shape channel required the application of external stress to the electrical leads simply for the purpose of setting up the IC packages for centrifugal testing. Once the testing was completed, the belts had to be shaken or the IC packages pried out from the channels in order to release the chips from the belt.
What is needed is a belt designed for easy loading and unloading of test chips from the centrifugal test rotor, without placing additional stress on the leads in order to assemble the chips for testing.